Tom Sandoval Concert Security Removes Fan with Ariana Madix Sign

Tom Sandoval couldn't escape the 'Scandoval' drama even while performing onstage ... giving one fan the boot from his Pittsburgh show, after she held up a "#TeamAriana" sign.

The "Vanderpump Rules" star was rocking out at Jergel's Rhythm Grille in Pittsburgh over Memorial Day weekend when a woman in the crowd flashed the paper sign to him, making it clear she was backing his ex-gf Ariana Madix.

The woman made sure Tom and everyone else saw it ... holding it high and doing a 360 with the sign in hand. Eventually, security came over and snatched the sign before she was escorted out by another.

Of course, Tom's been having a tough time since the news got out he cheated on Ariana with their costar Raquel Leviss ... putting a hard end to their 10-year relationship. And, although he's still been selling out shows for "Tom Sandoval & The Most Extras", it appears not everyone with a ticket is team Sandoval.

You'll recall, TS pissed off Pittsburgh officials, when he got caught complaining about Pennsylvania before he even got off the plane for the show.

TMZ broke the story ... Tom was on a plane over the weekend heading for Pittsburgh, when a fellow passenger overheard him on the phone with Raquel, telling her he was headed for "f***ing Pittsburgh."

Tom denied saying it and later told us, "The show we played in Pittsburgh was sold out and the people were incredible."